One of the most important aspects of firearms safety is to ensure you are using the correct ammunition for your firearm. Whether shooting a handgun, centerfire rifle, rimfire rifle or shotgun, every firearm requires a specific caliber (rifles and handguns) or gauge (shotgun) ammunition and there is virtually no room for error. Luckily, it is easy to make sure you are using the correct ammunition with your firearm.

But first, why is it so important? The first and foremost concern is safety. Firearms are engineered to handle specific calibers and cartridge types. Using incorrect or incompatible ammunition can lead to catastrophic failures, causing injury to the shooter, bystanders, or damage to the firearm itself. The pressure generated by a round that is too powerful for a firearm can cause irreversible damage to the firearm. Using the wrong size or load of ammunition can also lead to misfeeds, jams and other operating issues with your firearm.

How Do I Know I’m Using the Right Caliber/Gauge?

The cartridge or caliber designation can be found in several places. First, always double check your firearm’s barrel or slide. On all modern firearms, the cartridge designation is stamped or engraved on the barrel or slide of the firearm itself, so you know exactly what caliber or gauge your firearm is chambered for. Occasionally, on long guns, the caliber designation may be engraved on the bolt as well, but most often you will find it on the left side of the barrel.

When purchasing a new firearm, you should also always refer to the owner’s manual that came with the gun. The owner’s manual that comes with your firearm often includes detailed information about the firearm’s specifications, including the cartridge designation.

When loading your firearm, always check the cartridge headstamp first, which is located on the base of the cartridge or shell case where the primer is located. Here you will find stamped the caliber or gauge of the cartridge. It may include markings like the caliber (e.g., 9mm, .45 ACP), manufacturer’s name, and sometimes additional information. Make sure this always matches the caliber designation stamped on the firearm. 

When removing ammunition from a factory ammo box, the packaging will also prominently display information about the ammunition it contains. This information typically includes the cartridge designation (e.g., 9mm Luger, .223 Remington), bullet type, bullet weight, and other specifications. Always verify that the information on the box matches the markings on your firearm, as well as the cartridges in the box in the event someone has put the wrong ammo in the box.

Keep Ammunition Separate

Whether shooting at the range, transporting firearms and ammunition back and forth from home and the range or simply storing ammunition at home, always make sure you keep different types of ammo separate from each other.

Allowing different types of ammunition to be mixed on a shooting bench or even in a box or container can lead to accidentally attempting to load the wrong cartridge into the wrong firearm, which can cause a huge safety or operational issue. Never assume you know the caliber of a cartridge or shotgun shell as many look very similar in both appearance and size. For instance, 9mm and .380 ammo is very similar in size and can be easily confused if allowed to mix. 

Keeping ammunition separated is essential for safety, firearm functionality, and organization. Fortunately, it is extremely easy to keep it safe and identifiable with just a minimal amount of effort.